This invention relates to a control system for synchronous and sequentially correct control of groups of functional units in printing machines and in particular to a control system employing shift registers.
Control systems of the above-described type are known for example from the GDR Patent 89 856 in which a shift register is assigned to the sheet feeder and another shift register is assigned to the printing machine whereby both shift registers are connected in series.
From the U.S. Pat. No. 4,109,574, a control device for printing machines is known which is equipped with a shift register for performing the cyclic or synchronized control and moreover with a system for compensating nonoperative or dead times of operational units of the machine. The construction of such prior art devices necessitates very voluminous shift registers in order to achieve a synchronization with a plurality of periodic clock pulses for each cycle of 360.degree. with a relatively exact timing synchronization of the control of the functional groups and at sequentially correct time points. In the cases in which the timing or synchronization is made by means of two or three periodic timing signals per each 360.degree. there is no possibility to achieve any exact synchronized control of the functional units or groups of working elements of the machine at substantially correct time points; on the other hand, the size of the shift register is substantially reduced. In both cases, the expenditure for the control are further increased by the device for providing the necessary compensation of nonoperative times. Such a compensation device must be operative for momentary values of the rotary speed of the machine and is therefore very expensive.